Water-tube boiler



Dec. 20, 1955 GENZAEURO MATSUMOTO ET AL 3 9 WATER-TUBE} BOILER Filed March 2, 1953 2 Sheets-$heei 1 his BY jzzra P I @waa MAW/W1 United States Patent '0 WATER-TUBE BOILER Genzaburo Matsumoto, Kamakura, Kanagawa-ken, Ryo Masuda, Chigasaki, Kanagawa-ken, and Taro Ishida, Fujisawa, Kanagawa-ken, Japan Application March 2, 1953, Serial No. 339,788 4 Claims. (Cl. 122-185) The present invention relates to a water-tube boiler having a water preheating tank in the wall of a cylindrical furnace casing, two or more convection cylinders standing in the casing and slightly inclining their heads inwards, a partition plate in each of the said cylinders with water circulation gaps at its upper and lower ends, a plurality of semicircularly bent boiler-tubes obliquely and separately connecting the cylinders with each other in the two front and two back faces of the partition plates with an opposite inclination, a ceiling to bring about more efiicient use of the combustion gases, and a meandering superheating pipe passing through the combustion chamber.

The object of the present invention is to obtain a water-tube boiler of high thermal efiiciency effecting an active water circulation and evaporation, small in size and weight and easy to handle.

Most present-day water-tube boilers are designed with an integral water-cooled furnace to provide for maximum steam capacity and minimum furnace maintenance with a thermal efliciency of 30-40%. The present invention is an improved water-tube boiler with far higher thermal efiiciency, designed under special consideration of the arrangements and structures of boiler tubes and convection cylinders to speed up the convection or circulation of the boiler water as well as to arrest the local evaporation. Furthermore, in the present invention, the cylindrical casing is of double wall construction, the inner wall being slightly inclined inwardly from the bottom to the top of the furnace, and the space between the walls being used as a preheating tank to absorb the radiant heat of the furnace. Also, a novel combustion gas emission retarding ceiling is provided to bring about more efficient utilization of the combustion gases and to minimize the loss of the heat.

Further objects and advantages of the present invention will appear from the detail description.

In the accompanying drawings:

Figure 1 shows a longitudinal section of apparatus suitable for practicing the present invention, specially indicating, by dotted line, the direction of inclination of the front water tubes;

Figure 2 is a transverse section of the apparatus by the line ab of Figure l; and

Figure 3 is a graphic representation of the water circulation in the steam boiler of the present invention.

Referring to Figures 1 and 2, the furnace casing c is of double wall construction, the inner wall being slightly inclined inwardly from the bottom to the top of the furnace, and the space between said walls forming a cylindrical tank 1 serving as a preheater for absorbing radiant heat. Inside the furnace casing c, two convection cylinders 2 and 3 of the same size and shape are dis posed on the same level, and slightly inclining their heads inwardly to absorb the heat of combustion gas effectively. Within the said convection cylinders, partition plates and 11, having water circulation gaps 17 2,727,495 Patented Dec. 20, 1955 and 18 at their upper and lower ends, are fixed vertically, dividing each of the said cylinders into two equal chambers in front and back of the plates. The two front chambers of the cylinders are connected with each other by many oblique and semicircularly bent water-tubes 4', and also the two rear chambers of the cylinders are connected with each other by many semicircularly bent water-tubes 4 inclined in a direction opposite to that of the front chambers, thus arranging the tubes in a spiral form on the whole, so as to force all of the gas stream over as much boiler heating surface as practicable and to provide good internal circulation of the water.

A combustion chamber 6 and grates 5 of shaking type are provided in the lower part of the furnace. On the upper part of the furnace, there are arranged a chimney 9 and, right below it, a combustion gas retarding ceiling having many gas passages 8 in order to enable the boiler tubes 4 and 4' and cylinders 2 and 3 to absorb sufiicient heat from the gas stream before passing out of the furnace through the passages 8. Also, in the furnace, a mean dering superheating pipe 7 is connected with the top of one of the cylinders and passes longitudinally through the combustion chamber 6 to the outside to be used for heating purposes. Cylinders 2 and 3 are respectively connected with the water feeding pipes 13 and 16 which lead from a pipe 15 connected with the preheating tank 1. A pumping device 12 is installed in the pipe 15 to pump out the Water from the preheating tank 1 to the cylinders 2 and 3 and boiler tubes 4 and 4'.

In operation, the Water is first fed through an inlet cock 14 to the'preheating tank 1, convection cylinders 2 and 3 and boiler tubes 4 and 4' to a required level. A solid fuel is then fired on the grates 5. The generated hot combustion gas goes up in the combustion chamber 6 and heats all boiler-tubes 4 and 4' and convection cylinders 2 and 3, and is emitted from the chimney 9 after being effectively dispersed by the gas retarding ceiling before passing through passages 8. At the same time, the water in the preheater 1 or economizer is heated by the convection and radiation of the combustion gas. The water in the boiler tubes 4 and 4' begins to generate vapour and its gravity becomes small, and, on that account, the water in the boiler-tubes 4 at the back of the partition plates 16) and 11 runs up obliquely from the cylinder 2 to the cylinder 3, and the water in the boiler-tube 4' at the front of the partition plates 10 and 11 runs up oppositely from the cylinder 3 to 2, as shown in Figure 3. In other words, the water in the boiler is streamed up obliquely by the heat from the former to the latter and from the latter to the former of the two cylinders 2 and 3 in the front and back of the partition plates. In the two cylinders 2 and 3, there being inserted respectively the partition plates 10 and 11 having two water circulation gaps 17 and 13 at their upper and lower ends, the water in the bent tubes is naturally partitioned into inlet and outlet sides. The water in the outlet side being always higher in temperature than that in the inlet side, the former streams up and the latter streams down along the face and back of the partition plates 10 and 11, as shown by arrows in the Figure 3, thus causing a regular and equal convection or circulation of the boiler water and thereby increasing the thermal conductivity, evaporating capacity and thermal efficiency of the boiler to a great extent. Furthermore, the boiler pipes 4 and 4 arranged in the front and back of the furnace according to the present invention being connected with each other by the cylinders 2 and 3, the length of each pipe can be shortened this much, and this feature goes to do away with any danger of local evaporation as seen in the boilers hitherto used.

The boiler of the present invention is conveniently employed in case a big quantity of hot water is required immediately, i. e. for steam stove, public and family baths etc. The experiments of this invention on a family bath of 200 litres water show that only 14 minutes in summer and 23 minutes in Winter are required for warming it up to 45 degrees C.

While a preferred embodiment according to the invention has been illustrated and described, it is understood that various modifications may be resorted to Without departing from the spirit and pended claims.

We claim:

1. In a water-tube boiler, a cylindrical furnace casing comprising a pair of spaced concentric walls defining therebetween a tank for the preheating of water, a pair of convection cylinders closed at their opposite ends and disposed in said casing, a plurality of vertically spaced and obliquely disposed boiler tubes connecting said cylinders, a partition plate positioned inside each of said cylinders, said plates having water circulation gaps at their upper and lower ends, and pipe means connected between each of said cylinders and said tank for conveying preheated water from the latter to said cylinders.

2. In a water-tube boiler as claimed in claim 1, wherein the partition plates are positioned lengthwise of the cylinders and divide each cylinder into two equal parts, and wherein the plurality of vertically spaced and obliquely disposed boiler tubes comprise a plurality of semicircw larly bent boiler tubes connecting the cylinders separately at the front and back of the partition plates with the tubes at the front of the plate at opposite inclination to the tubes at the back of the plates, so as to supply water of different temperatures to the front and back of the partition plates thereby causing the water in each cylinder to circulate equally up and down on both sides scope of the apof the partition plates by passing through the upper and lower circulation gaps.

3. In a water-tube boiler as claimed in claim 1, wherein the inner wall of the concentric casing walls is inclined inwardly slightly from the bottom of the casing to the top thereof to enable the wall to absorb efiectively the radiant heat, and wherein said cylinders are slightly inclined inwardly from the bottom to the top of said casing, a combustion gas retarding ceiling having a plurality of gas passages, said ceiling through the medium of said passages retardingtthe flowoi gas from the casing to enable the cylinders to; absorb sufiicient heat from said gas stream, and a meandering superheating pipe connectedto the upper part of one of said cylinders and longitudinally passing through the combustion chamber.

4. A water-tube boiler as claimed in claim 1, wherein the tank for preheating water is of low pressure construction and independent of the boiler steam pressure, and wherein the inner wall of said tank is inclined inwardly of said boiler casing, and the cylinders are inclined toward each other, and pipe means including a pump is interconnected between said tank and said cylinders.

References Cited in the file of this patent 

